JPH0650754A - Inclination-angle and vibration sensor and inclination-angle measuring method using the same - Google Patents

Abstract

PURPOSE:To perform an inclination-angle and vibration measurement with high accuracy by a simple constitution whose error factor is small by a method wherein the relative displacement amount between a movable scale and a fixed scale is read out and the displacement of a pendulum is detected directly. CONSTITUTION:An inclination-angle and vibration sensor 10 is provided with a housing 17 which is composed of a base 12, a housing frame 14 and an upper lid 16, with a pendulum 22 composed of a wire spring 18 and a weight 29 which are held in the central part of the upper lid 16 and which are suspended inside the housing 17, with a displacement detection means 24 composed of an opto- electronic encoder and with an inclination-angle and vibration operation means 25. In addition, the displacement detection means 24 is provided with a movable scale 28 installed on the rear surface of the weight 20, with a fixed scale 30 attached to the base 12 in a position faced with the movable scale 28 and with a displacement-photometric part 32 arranged and installed at the lower part of the fixed scale 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt angle / vibration sensor and a tilt angle measuring method for measuring a tilt angle at a current position and vibration such as an earthquake. More specifically, it detects a two-dimensional displacement of a pendulum weight. The present invention relates to a tilt angle / vibration sensor for measuring a tilt angle, vibration amplitude, frequency, etc., and a tilt angle measuring method for measuring an absolute tilt angle with respect to a horizontal plane.

[0002]

2. Description of the Related Art In recent years, it has become necessary to measure an inclination angle with high precision in an operation control device or the like, and various inclination angle sensors are known. On the other hand, various vibration sensors have been developed to detect vibrations such as earthquakes and appropriately control the operation of elevators and the like to ensure the safety thereof. One such tilt angle sensor or vibration sensor is one that detects the amount of displacement of the pendulum and measures the two-dimensional tilt angle, the magnitude of the amplitude of the earthquake, etc., the frequency, the direction of the epicenter, etc., based on the detection results. Are known. The pendulum displacement detecting means in such a sensor is roughly classified into (1) one utilizing change in capacitance and (2) one utilizing change in magnetic field.

[0003]

However, in the case of using the displacement detecting means which utilizes the change in electrostatic capacitance described above, a capacitor having a very small capacitance of about several pF is installed at the lower end of the pendulum, and the capacitor is used. Since the above position is detected based on a minute change in the amount of stored electricity, the amount of stored electricity is easily affected by the distributed capacity of the pendulum structure or the wire of the circuit system, etc., making it difficult to detect displacement with high accuracy. Met. Further, when using the displacement detection means utilizing the change of the magnetic field described above, since a magnet is installed at the lower end of the pendulum and the change of the magnetic field due to the vibration of the pendulum is detected by a magnetoresistive element or the like, The detected amount is easily affected by temperature drift and the like, and it is difficult to obtain a highly accurate one. Also, in terms of manufacturing technology, assembly of the device is troublesome, which is a problem. The present invention has been made in view of such circumstances, and an object thereof is to detect an amount of displacement of a pendulum with high accuracy and to make an angle of inclination that facilitates manufacture of the device.
An object of the present invention is to provide a vibration sensor and a tilt angle measuring method capable of measuring an absolute tilt angle with respect to a horizontal plane with high accuracy.

[0004]

[Means for Solving the Problems] Inclination angle according to the present application
In short, the vibration sensor has a movable scale installed on the lower surface of the pendulum weight, and a fixed scale installed on the housing bottom wall (base) that faces the movable scale.
It is characterized in that the two-dimensional displacement of the weight of the pendulum is detected by detecting the change in the relative position of these two scales, and the information on the tilt angle and the vibration is measured based on the detection result. That is, in the tilt angle sensor according to claim 1 of the present application, the housing that covers the main part of the sensor and the weight are attached to the lower portion of the linear body that has elasticity in the direction perpendicular to the length direction. A pendulum hanging from the upper wall portion of the weight, a movable scale installed on the lower surface of the weight, and arranged to face the movable scale.
Displacement detecting means having a fixed scale fixed to the bottom wall of the housing, for detecting two-dimensional displacement of the weight in a direction perpendicular to the lengthwise direction of the linear body, and the displacement detecting means. And an inclination angle calculating means for calculating an inclination angle at the position where the bottom wall portion of the housing is disposed based on the displacement amount detected by.

The vibration sensor according to claim 2 of the present application comprises a housing that covers the main part of the sensor, and a weight attached to the lower portion of a linear body having elasticity in a direction perpendicular to the length direction. A pendulum hanging from the upper wall portion of the housing, a movable scale installed on the lower surface of the weight, and a fixed scale fixed to the bottom wall portion of the housing that is arranged to face the movable scale. A displacement detection means for detecting a two-dimensional displacement of the weight in a direction perpendicular to the lengthwise direction of the linear body, and a bottom wall portion of the housing based on the displacement amount detected by the displacement detection means And a vibration calculation means for calculating the information of the vibration at the installation position. Here, the "sensor main part" includes at least a pendulum and a displacement detecting means. Further, the "housing" does not necessarily cover the main part of the sensor in all directions.
Furthermore, the above "vibration information" means the amplitude and frequency of the vibration, and does not exclude the inclusion of the direction of the epicenter such as an earthquake.

Further, the tilt angle measuring method according to claim 3 of the present application comprises: a sensor rotating step of rotating the tilt angle sensor based on the central axis of the tilt angle sensor; and a pre-rotation position and a post-rotation position. A displacement detecting step of detecting a relative displacement amount between the movable scale and the fixed scale, and an inclination angle calculation for calculating an absolute inclination angle with respect to a horizontal plane at a disposition position of the bottom wall portion of the housing based on the detected displacement amount. And a process. In the tilt angle measuring method according to claim 4 of the present application, the sensor is rotated by a predetermined angle in the sensor rotating step, and the tilt angle calculating step is performed based on the rotation angle and the displacement amount detected in the displacement detecting step. Where the absolute tilt angle is

[Mathematical formula-see original document] sin θ ≈ [R / (1-cosα)] · (3EI / Wl ³ ) where θ: absolute inclination angle at the position where the bottom wall of the housing is installed R: relative displacement between the movable scale and the fixed scale α: Sensor rotation angle (0 ° <α <360 °) W: Concentrated load at the center of gravity of the weight E: Linear elastic modulus of the linear body I: Moment of inertia of the linear body l: Pendulum linear body supporting portion It is characterized in that it is calculated by the distance from the bottom position of to the center of gravity of the weight.

Further, in the tilt angle measuring method according to claim 5 of the present application, the sensor is rotated at least twice at an arbitrary angle in the sensor rotating step, and the movable state is set at a pre-rotation position and each post-rotation position. Obtain the radius of the circumscribed circle of the polygon connecting the respective displacement points of the relative displacement of the scale and the fixed scale, based on the radius value, the absolute tilt angle in the tilt angle calculation step,

[Mathematical formula-see original document] sin θ≈r · (3EI / Wl ³ ) where θ: absolute inclination angle at the position where the bottom wall of the housing is installed r: radius of the circumscribed circle of the polygon connecting the displacement points W: center of gravity of the weight Concentrated load in E: Linear elastic modulus of linear body I: Moment of inertia of linear body l: Distance from the lowest position of the linear body supporting portion of the pendulum to the center of gravity of the weight.

[0008]

In the tilt angle sensor according to the present application, the movable scale installed on the lower surface of the pendulum weight and the displacement detecting means for detecting the relative displacement of the fixed scale installed on the housing facing the movable scale. The two-dimensional displacement of the pendulum is detected, and the tilt angle calculation means calculates the tilt angle based on the detection result. here,
A method for obtaining the tilt angle from the displacement detection result in the tilt angle calculation means will be described. That is, when the center axis direction of the sensor is inclined by θ with respect to the direction parallel to the gravity direction, the deflection amount (two-dimensional displacement amount) δ of the center of gravity P of the weight is

## EQU5 ## It is represented by δ≈ (Wl ³ / 3EI) × sin θ. However, W: concentrated load at the center of gravity P of the weight l: distance from the lowest position of the linear body supporting portion of the pendulum to the center of gravity P of the weight E: modulus of elasticity (Young's modulus) of the linear body I: line Therefore, the inclination angle θ can be obtained from the equation 5 by detecting the deflection amount δ by the displacement detecting means.

In the tilt angle measuring method according to the present application, the sensor is rotated around the central axis of the sensor, and the deflection amount δ is detected based on the displacement amount at the position before and after the rotation of the weight. There is. That is, when the center axis direction of the sensor is inclined by θ with respect to the direction parallel to the direction of gravity, when the sensor is rotated about the center axis, the center of gravity P of the weight is displaced according to the deflection amount δ. . Therefore, the deflection amount δ is obtained by detecting the displacement amount, and the inclination angle θ with respect to the gravity axis of the central axis of the sensor, that is, with respect to the horizontal plane at the installation position of the housing bottom wall portion can be measured. Further, the sensor is set to a predetermined angle α (0
The relation between the relative displacement amount R of the movable scale and the fixed scale and the deflection amount δ when rotated is as follows.

## EQU6 ## It is represented by δ = R / (1-cosα). Therefore, from the above equations 5 and 6,

[Equation 7] sin θ≈ [R / (1-cosα)] · (3EI / Wl ³ ) Therefore, if the relative displacement amount R is detected by the displacement detecting means, the inclination angle θ is calculated from the above Equation 7. You can ask.

Further, the deflection amount δ can be obtained by rotating the sensor at least twice at an arbitrary angle. That is, when the sensor is rotated,
The trajectory along which the center of gravity P of the weight is displaced draws a circle with the central axis of the sensor as the center of rotation and the deflection amount δ as the radius. Then, for example, when the sensor is rotated twice at an arbitrary angle, a circumscribed circle of a triangle connecting the displacement points of the center of gravity P of the weight at the pre-rotation position and the post-rotation position of the sensor becomes the orbit circle, The center point of the circumscribed circle is located on the center axis of the sensor. Therefore, if the displacement amount after the rotation is detected and the radius r of the circumscribed circle is obtained in the displacement detection step, the relationship between the radius r and the deflection amount δ becomes

## EQU00008 ## Since r = .delta., The tilt angle .theta.

Mathematical Expression 9 sin θ≈r · (3EI / Wl ³ ) can be used for the calculation.

Next, in the vibration sensor according to the present application, the two-dimensional displacement of the pendulum weight is detected in the same manner as the tilt angle sensor, and the vibration calculation means calculates the vibration information based on the detection result. It has become. here,
A method of obtaining information on the vibration from the detection result of the displacement in the vibration calculation means will be described. That is, when the center axis direction of the sensor is set parallel to the direction of gravity, and when the sensor is subjected to vibration of _one- sided amplitude X ₁ and angular frequency ω, the vibration equation at the center of gravity P of the weight is expressed by the following formula 10.

[Equation 10] However, W: concentrated load at the center of gravity P of the weight l: distance from the lowest position of the linear body supporting portion of the pendulum to the center of gravity P of the weight E: modulus of elasticity (Young's modulus) of the linear body I: line Moment of inertia C: Damping coefficient g: Acceleration of gravity Therefore, if the displacement amount x of the weight is detected by the displacement detecting means, the half amplitude X ₁ of vibration and the angular frequency ω can be obtained from the above equation 10. it can.

The equation 10 is an expression for obtaining information on vibration in one direction (x direction), but information on vibration in a direction (y direction) orthogonal to this direction can also be obtained by the same vibration equation. Therefore, it is possible to two-dimensionally determine the nature of the vibration that is actually occurring from the obtained information on both the x-direction and y-direction vibrations. For example, it is possible to know the direction of the epicenter of the earthquake. Become. As described above, the tilt angle / vibration sensor according to the present application uses the movable scale and the fixed scale for the displacement of the pendulum, unlike the conventional technology that detects the displacement of the pendulum by using the change of the electrostatic capacity or the magnetic field. Since the information is directly detected and the information on the tilt angle and the vibration can be easily obtained by using a predetermined mathematical expression based on the detection result, the configuration is simple and the error factor is extremely small. Therefore, the information on the tilt angle and the vibration can be measured with high accuracy, and the assembly of the sensor can be facilitated. Further, in the tilt angle measuring method according to the present application, the sensor is rotated about the central axis of the sensor, and the pendulum is displaced according to the absolute tilt angle with respect to the gravity axis (horizontal plane). Detect
It is possible to measure the absolute tilt angle with high accuracy using a predetermined mathematical expression based on the detection result.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a tilt angle / vibration sensor according to an embodiment of the present invention. FIG. 1A is a plan view, FIG. 1B is a side sectional view, and FIG. 1C is a front sectional view. It is a figure. The inclination angle / vibration sensor 10 shown in the figure includes a housing 17 including a base 12, a housing frame 14, and an upper lid 16,
A pendulum 22 that is held in the central portion of the upper lid 16 and is suspended in the housing 17 and that includes a wire spring 18 and a weight 20.
And a displacement detection means 24 composed of a photoelectric encoder and a tilt angle / vibration calculation means 25. The housing frame 14 has the same cylindrical shape and engages with the base 12 and the upper lid 16 to keep the inside of the housing 17 in a sealed state. A transparent damping oil 26 is enclosed in the housing 17.

Further, the wire spring 18 of the pendulum 22 has a predetermined elasticity (Young's modulus E) in a direction perpendicular to the lengthwise direction thereof, and the central portion of the column-shaped weight 20 (weight W) is provided. The weight 20 is held so as to penetrate therethrough. The displacement detecting means 24 includes a movable scale 28 installed on the lower surface of the weight 20, a fixed scale 30 attached to the base 12 at a position facing the movable scale 28, and a fixed scale 30 disposed below the fixed scale 30. The displacement photometer 32 is provided. The displacement photometric unit 32
A lead wire 34 extends downward from each of the parts, and the plurality of lead wires 34 are bound by a covered wire 36 and connected to a connector 40 held by a connector holder 38. The connector 40 is connected to a cable connected to the tilt angle / vibration calculating means 25, whereby the displacement information detected by the displacement detecting means 24 can be sent to the calculating means. Further, the tilt angle / vibration calculating means 25 calculates the tilt angle, the amplitude and frequency of vibration, etc. according to a predetermined calculation formula based on the input displacement information. The tilt angle / vibration sensor 10 according to the present embodiment is roughly configured as described above.

Next, the tilt angle detecting mechanism of the sensor 10 of this embodiment will be described with reference to FIG. FIG. 2A shows a case where the direction of the central axis of the wire spring 18 is parallel to the gravity direction. It should be noted that the distance from the lower end of the housing upper lid 16 holding the pendulum 22 to the center of gravity P of the weight 20 is l. FIG. 2B shows a case where the sensor is tilted by an angle θ. When the sensor is tilted in this way, the wire spring 18 has elasticity and is deflected by the load W of the weight 20 to position the weight 20. Indicates a position 20b indicated by a two-dot chain line, which is slightly deviated from the position indicated by a solid line in FIG. That is, the center of gravity of the weight 20 is located on the point P ′ displaced by the distance δ from the point P on the line forming an angle θ with the gravity direction. That is, the inclination angle θ and the distance δ representing this amount of deflection are

## EQU11 ## There is a relationship of δ≈ (Wl ³ / 3EI) × sin θ. However, W: concentrated load at the center of gravity P'of the weight 20 (assuming the weight of the wire spring 18 is 0) E: longitudinal elastic modulus (Young's modulus) of the wire spring I: moment of inertia of the wire spring 18 The displacement angle detecting means 24 detects the distance .delta., And the inclination angle / vibration calculating means substitutes the detected value .delta.

Here, the detection of the distance δ by the displacement detecting means 24 is performed by detecting the amount of displacement from the center of gravity P of the weight 20 to the center of gravity P ', as described above. Therefore, when the direction of the central axis of the wire spring 18 in FIG. 2A changes from the state parallel to the direction of gravity to the state in which the angle θ in FIG. Distance δ
Can be detected, but cannot be detected because the angle θ of the sensor in the state of (b) in the figure at the start of detection does not appear as a displacement amount in the state as it is. That is, when the sensor changes a tilt angle from a certain state, the changed relative tilt angle can be detected as the displacement amount, but the absolute tilt angle of the sensor with respect to the gravity axis (horizontal plane) in the current state is In that condition, it cannot be detected as the displacement amount. Further, even when the inclination angle is changed from FIG. 2 (a) to FIG. 2 (b), if there is a deviation between the direction of the central axis of the wire spring 18 and the direction of gravity in FIG. 2 (a), The deviation is included in the measured absolute tilt angle as an error, and the measurement accuracy is reduced.

Therefore, in the present embodiment, the sensor is rotated with the central axis of the sensor (the central axis of the wire spring 18) as a reference axis, and the weight is displaced according to the absolute inclination angle.
A tilt angle measuring method for obtaining an absolute tilt angle from the displacement amount is used. That is, as shown in FIG. 3, when the center axis of the sensor is inclined with respect to the gravity axis (the reference plane on which the sensor is installed is inclined with respect to the horizontal plane) by an angle θ, the deflection amount δ of the weight 20 is as described above. As described above, it is represented by the above-mentioned formula 11. Here, for example, when the sensor is rotated 180 degrees on the reference plane about the reference axis, the center point of the lower surface of the weight 20 is relative to the base 12 from the point a before rotation as shown in FIG. The displacement is relative to the symmetry point -a about the upper point o. Since the distance between the point a and the point o is the deflection amount δ of the weight 20, the point a and the symmetry point −a
The displacement amount R ₁₈₀ between

## EQU12 ## R ₁₈₀ = 2A≈2δ where A is the distance between the point a and the point o.

[Number 13] _{sinθ ≒ (R 180/2)} · (3EI / W
The relationship of l ³ ) is established. Therefore, the displacement amount R ₁₈₀ is detected by the displacement detecting means 24, and the displacement amount R ₁₈₀
By substituting the value of, the absolute tilt angle θ can be obtained.

Further, the displacement amount Rx of each of the components in the x-axis direction and the y-axis direction which are orthogonal to each other on the reference plane.
By detecting Ry and Ry, the two-dimensional tilt angle can be measured. Although the sensor rotation angle is set to 180 degrees in the above-mentioned embodiment, it is not necessary to set it to this angle. That is, when the rotation angle of the sensor is 90 degrees,
The relationship between the displacement amount R ₉₀ and the deflection amount δ is

[Formula 14] R ₉₀ = A≈δ where A is the distance between the point a and the point o.

Since there is a relationship of sin θ≈R ₉₀ · (3EI / Wl ³ ), the absolute inclination angle θ can be obtained by substituting the value of the displacement amount R _{90 into} the equation 15. That is, the sensor rotation angle α (0 ° <α <360
In °), the relationship between the displacement amount R and the deflection amount δ is

[Equation 16] δ = R / (1-cos α), and from Equation 16 and Equation 11,

Since sin θ≈ [R / (1-cosα)] · (3EI / Wl ³ ) is satisfied, if the rotation angle α is a known angle, the inclination angle θ can be obtained from the formula 17. Of.

Further, the rotation of the sensor is 2 at an arbitrary angle.
It is preferable that the deflection is performed twice, the weight 20 is moved relative to the base 12 twice, and the deflection amount δ is obtained from the position before rotation of the weight and the displaced position after each rotation. FIG. 4 shows the displacement of the weight 20 when the sensor is rotated twice at an arbitrary angle. That is, when the sensor is rotated at an arbitrary angle, the center point of the lower surface of the weight 20 is from the position of the point P ₁ shown in FIG. Move to the position of point P ₂ shown in B). Furthermore, when the sensor is rotated again at an arbitrary angle, the center point of the lower surface of the weight 20 moves to the position of point P ₃ shown in FIG. Then, the points P ₁ and P
The center point O of the circumscribed circle of the triangle connecting ₂ and the point P ₃ is located on the center axis of the sensor, and the distance from the center point O to the points P ₁ , P ₂ , and P ₃ , that is, the circumscribed line The radius of the circle is the amount of deflection of the weight 20. Therefore, the coordinates of three points are obtained from the respective displacement amounts of the points P ₁ , P ₂ , and P ₃ detected by the displacement detection means 24, and the radius r of the circle where the three points are located on the same circumference. From the above equation 11 and the radius r, the absolute tilt angle θ can be obtained by

(18) sin θ≈r · (3EI / Wl ³ ) According to the method described above, since the rotation angle of the sensor can be arbitrarily set, a measurement error due to the variation of the rotation angle caused when the sensor is rotated at the known predetermined angle does not occur, and the absolute tilt angle can be measured with high accuracy.

Next, the vibration detecting mechanism of the sensor 10 of this embodiment will be described with reference to FIG. That is, the vibration equation in the x-axis direction (the arrow x direction in FIG. 3) of the center of gravity P when the sensor 10 is subjected to vibration due to an earthquake (one-sided amplitude X ₁ , angular frequency ω ₁ ) is

[Formula 19] It is represented by. However, W: concentrated load at the center of gravity P of the weight 20 (assuming the weight of the wire spring 18 is 0) E: longitudinal elastic modulus (Young's modulus) of the wire spring I: moment of inertia of the wire spring C: damping Coefficient g: Gravitational acceleration When the central axis of the wire spring 18 coincides with the direction of gravity in the equation (19), the position of the central axis is set to x = 0.

Therefore, if the displacement detecting means 24 detects the displacement amount x and the inclination angle / vibration calculating means 25 substitutes the detected value x in the above equation 19, the half amplitude X ₁ of vibration and the angular frequency ω ₁ are obtained. You can ask. Further, the vibration equation of the center of gravity P in the gravity direction and the y-axis direction orthogonal to the x-axis is

[Equation 20] It is represented by. However, the codes of W, E, I, C, and g are defined in the same manner as the code of the above-mentioned equation 19. Therefore, if the displacement detecting means 24 detects the displacement amount y and the inclination angle / vibration calculating means substitutes the detected value y in the equation 20, the half amplitude Y ₁ and angle of the vibration are the same as the vibration in the x-axis direction. The frequency ω ₁ can be obtained.

The vibration in the x-axis direction thus obtained and y
If the vibrations in the axial direction are combined, the actual vibration amplitude, frequency,
Furthermore, it is possible to obtain vibration information such as the epicenter direction of the earthquake. By the way, a characteristic of the present invention is that the pendulum 2
The displacement amount of 2 is detected by a displacement detecting means which is a combination of a movable scale and a fixed scale. Therefore, in this embodiment, a photoelectric encoder in which a movable scale 28 and a fixed scale 30 are combined is used as the displacement detecting means 24. I am using. Hereinafter, the displacement detecting means 24 including this photoelectric encoder will be described. 6 is a vertical sectional view showing an example of the photoelectric encoder 24 according to the present invention, and FIG. 7 is a sectional view taken along the line I-I shown in FIG. In FIG. 6, one surface of the fixed scale (hereinafter referred to as index scale) 42 in FIG. 6 has one light emitting element 46 and eight light receiving elements 48a, 48b, and
... 48h is arranged. The lead wires of the light emitting element 46 and each light receiving element 48 are fixed to the printed circuit board 50.

On the other hand, a movable scale (hereinafter referred to as a main scale) 44 is provided with a first grating 52 shown in FIG. 8, and the first grating 52 is a rectangular island-shaped reflection grating portion 54 ₁₁ , 54 _{12 in a} matrix form. ... 54 _1n , 54 ₂₁ , 54 ₂₂ ... 54
_{2n, ..., 54 m1, 54} m2, consisting of cross-shaped reflective grating comprising ... 54 _mn. The arrangement of the lattice portions 54 in the X-axis (column) direction constitutes a lattice having a pitch P ₁ parallel to the Y-axis, and the arrangement of the lattice portions 54 in the Y-axis (row) direction is a pitch P ₁ parallel to the X-axis. 'Constitute the lattice. On the other hand, the index scale 46, as is apparent from FIG.
. 58h. The second grating 56 is a cross-shaped transmission grating including the triangular transmission grating portions 60a, 60b, ... 60d corresponding to the light emitting elements 46. The third gratings 58a, 58b, ... 58h are transmission gratings corresponding to the light receiving elements 48a, 48b ,.

Therefore, the light L emitted from the light emitting element 46
Are reflected by the first grating 52 via the second grating portions 60a, 60b, ... 60d, and the reflected light is reflected by the third gratings 58a, 58.
58h via light receiving elements 48a, 48b, ...
The light is received by h. As described above, in the photoelectric encoder according to the present embodiment, the second grating portions 60a and 60b, the first grating portion 54 are arranged in the column direction, and the third grating portion 58a is provided with respect to the relative movement in the X direction. , 58b, 58c, 58d and the light receiving elements 48a, 48b, 48c, 48d each function as a three-lattice displacement detector. Further, with respect to the relative movement in the Y direction, the second lattice portions 60c and 60d, the first lattice portion 54 are arranged in the row direction, and the third lattice portions 58e, 58f, and 5 are arranged.
8g and 58h each function as a three-lattice type displacement detector.

That is, the three-lattice displacement detector detects the amount of displacement by the change in the overlapping of three gratings as shown in FIG. 10 (Journal of the optical societ).
y of America, 1965, vol.55, No.4, p373-381). Figure 10
The three-grating type displacement detector shown in FIG. 2 includes a second grating 56 and a third grating 58 arranged in parallel, a first grating 52 arranged in parallel so as to be relatively movable between the two gratings 56, 58, and the second grating. It includes a light emitting element 46 arranged on the left side of the grating 56 in the drawing, and a light receiving element 48 arranged on the right side of the third grating 58 in the drawing. Then, the light emitted from the light emitting element 46 reaches the light receiving element 48 via the second grating 56, the first grating 52, and the third grating 58, and the light receiving element 48 has the respective gratings 56, 52, 58.
Photoelectrically converts the illumination light limited by the preamplifier 6
It is amplified by 2 to obtain the detection signal s. Where the first grid 52
However, when the light moves relative to the second grating 56 and the third grating 58 in, for example, the x direction, the amount of light shielded by the gratings 56, 52, and 58 in the illumination light from the light emitting element 46 gradually changes and is detected. The signal s is output as a substantially sine wave. The pitch P ₁ of the first grating 52 corresponds to the wavelength P of the detection signal s, and the relative movement amount of the reference grating 52 is measured based on the wavelength of the detection signal s and its division value.

Therefore, the first grating 52 is connected to the main scale 4
4, by installing the second grating 56 and the third grating 58 on the index scale 42, respectively, the relative movement amount of both scales 44, 42, that is, the pendulum 22 and the base 1.
The relative movement amount of 2 can be detected. Further, in the present embodiment, the arrangement of the lattice portions 54 of the first lattice 52 in the X-axis direction is a lattice having a pitch P ₁ parallel to the Y-axis, and the arrangement of the lattice portions 54 in the Y-axis direction is the X-axis. To form a grating having a pitch P ₁ 'parallel to. In addition, the lattice portion 60 of the second lattice 56
A lattices parallel to the Y axis and having a pitch P ₂ are formed on a and 60b, and lattice portions 60c and 60d are parallel to the X axis and have a pitch P ₂ '.
The grid of is formed.

Further, the third lattice 58a has an Ax phase lattice, the third lattice 58b has an Ax 'phase lattice, and the third lattice 5
8c has a Bx phase lattice, the third lattice 58d has a Bx ′ phase lattice formed at a pitch P ₃ parallel to the Y axis, and the third lattice 58e has an Ay phase lattice and a third lattice. 58
are formed in parallel with a pitch P ₃ 'on the' lattice, grating for By phase Third grid 58 g, By the third grating 58h for phase 'X-axis respectively grating for phase Ay to f . Therefore, when Ax = 0 °, Ax ′ = 180 ° (1 / 2P ₃ different) Bx = 90 ° (1 / 4P ₃ different) Bx ′ = 270 ° (3 / 4P ₃ different) with respect to Ax When Ay = O °, '(different Ay 1 / 2P ₃₎ = 180 °' to Ay By a = 90 ° (1 / 4P ₃ 'differs) By a' = 270 ° and (3 / 4P ₃ 'different) It is graduated so that As a result, from the light receiving elements 48a, 48b, 48c and 48d, respectively, π
Ax phase, Ax 'phase, Bx phase, Bx' with a phase difference of / 2
A phase signal can be obtained, and an Ax phase output differentially amplified by the Ax phase-Ax 'phase and a Bx phase output differentially amplified by the Bx phase-Bx' phase are obtained. And the A
The relative movement direction of the scale in the X direction is discriminated from the phase shift direction of the x-phase output and the Bx-phase output, and the detection signal is electrically divided to detect the displacement amount with high resolution.

On the other hand, the light receiving elements 48e, 48f, 48g,
Ay phase with phase shift of π / 2 from 48h,
Ay′-phase, By-phase, and By′-phase signals can be obtained, and the phase discrimination and relative movement distance of the scales 42 and 44 in the Y direction can be detected in the same manner as the X direction. As described above, according to the photoelectric encoder, it is possible to detect the moving direction and the moving distance in the X direction and the Y direction. Further, in this embodiment, the column-direction lattice portions 54 for detecting movement in the X direction and the row-direction lattice portions 54 for detecting movement in the Y direction are provided with different pitches. That is,
The pitch in the column direction is engraved with a relatively coarse pitch P ₁ , which enables high-speed reading of the movement in the X direction. on the other hand,
A relatively fine pitch P ₁ 'is engraved in the row direction, and high-resolution reading of movement in the Y direction is possible.

As described above, the respective pitches can be determined in accordance with the movement characteristics of the pendulum 22, and the lattices can be formed in accordance with the pitch by the same manufacturing method as in the prior art, very accurately. In addition, for example, it is preferable to configure the pitch as follows. P ₁ = 40 μm (light portion length = dark portion length = 20 μm) P ₂ = 160 μm (bright portion length = 40 μm, dark portion length = 120 μ
m) P ₃ = 80 μm (light portion length = dark portion length = 40 μm) P ₁ ′ = 20 μm (bright portion length = dark portion length = 10 μm) P ₂ ′ = 80 μm (light portion length = 20 μm, dark portion length = 60 μm) P ₃ ′ = 40 μm (Bright portion length = Dark portion length = 20 μm) By thus setting the pitch of the second grating to be larger than the pitch of the first grating and setting the length of the light transmitting portion to be equal to or less than the pitch of the first grating. , The independence (incoherency) between the illumination light transmitted through the second grating is improved, and the SN ratio of the detection signal is increased. Therefore, signal processing becomes easy, and highly accurate displacement detection becomes possible.

It is also preferable that the pitch structure is as follows. P ₁ = 100 μm (light portion length = dark portion length = 50 μm) P ₂ = 400 μm (light portion length = 100 μm, dark portion length = 300
μm) P ₃ = 200 μm (light part length = dark part length = 100 μm) P ₁ ′ = 40 μm (bright part length = dark part length = 20 μm) P ₂ ′ = 160 μm (bright part length = 40 μm, dark part length = 120 μm
m) P ₃ '= 80 μm (light portion length = dark portion length = 40 μm) Furthermore, it is preferable to configure the pitch as follows, for example. P ₁ = 20 μm (light portion length = dark portion length = 10 μm) P ₂ = 20 μm (bright portion length = dark portion length = 10 μm) P ₃ = 20 μm (bright portion length = dark portion length = 10 μm) P ₁ ′ = 10 μm (bright portion length = dark portion length) = 5 μm) P ₂ '= 10 μm (light portion length = dark portion length = 5 μm) P ₃ ' = 10 μm (bright portion length = dark portion length = 5 μm) In this way, the pitches of the first grating, the second grating, and the third grating are made equal. If the lattice spacing between the main scale 44 and the index scale 42 is d, P ₁ = 20 μm> P ₁ '= 10 μm in this example. Therefore, the lattice spacing d between the main scale 44 and the index scale 42 is d ≧ P _By setting ₁ ² / 2λ, it is possible to realize an XY encoder whose output hardly fluctuates in response to fluctuations in the lattice spacing d. Note that P ₁
When = P ₁ ', either _one may be adopted. The features of this configuration are as follows: (1) When 1 pitch P _{1 is} sent in the X direction, the output signal is output by 2 pitches P ₁ and an optical split signal is obtained.
The electric division circuit is easily configured. (2) Since it is tolerant of fluctuations in the lattice spacing d, for example, P
Suitable for systems with fine pitch where ₁ or P ₁ 'is 40 μm or less.

Further, it is also preferable that the pitch structure is as follows. P ₁ = 40 μm (light portion length = dark portion length = 20 μm) P ₂ = 80 μm (bright portion length = dark portion length = 40 μm) P ₃ = 80 μm (bright portion length = dark portion length = 40 μm) P ₁ ′ = 10 μm (bright portion length = dark portion length) = 5 μm) P ₂ '= 10 μm (bright part length = dark part length = 5 μm) P ₃ ' = 10 μm (bright part length = dark part length = 5 μm) With this configuration, when one pitch is sent in the X-axis direction, 1 pitch P An output signal of ₁ is obtained. 1 in the Y-axis direction
When the pitch P ₁ 'is sent, an output signal of 2 pitches P ₁ ' is obtained. Therefore, the resolution is coarse in the X-axis direction, high-speed detection,
The Y-axis direction has high resolution and is suitable for low-speed detection. Further, the first grating 52 can be formed over a wide range, and the detection range can be widened. Also, the first lattice 52
The shape of can be arbitrarily determined in consideration of the relative movement distance of the main scale 44 and the index scale 42. It is also possible to configure the matrix-shaped island-shaped grating 54 provided on the main scale 44 as the transmissive portion and the non-island-shaped grating portion 64 as the reflective portion.
On the other hand, FIG. 11 is a vertical sectional view showing the basic structure of a photoelectric encoder 124 according to another embodiment of the present invention, and FIG. 12 is taken along line IX-IX shown in FIG. A cross-sectional view of is shown.

In the figure, the index scale 14
11, one light emitting element 146 and four light receiving elements 148a, 148b, ... 148d are arranged on the lower surface in FIG. The lead wires of the light emitting element 146 and each light receiving element 148 are fixed to the printed circuit board 150. Further, the main scale 144 has a striped grating 152 shown in FIG.
The striped grating 152 is provided with a transparent surface 154 in the center thereof, and the transparent surface 154 extends outward from the transparent surface 154.
A square V-shaped chromium vapor deposition reflecting surface 164 and a transparent surface 154 are alternately and repeatedly formed by two sets of parallel lines parallel to the X-axis and Y-axis directions. Further, one transparent surface 154 having a square shape and one reflecting surface 164 adjacent to the outside of the transparent surface 154 are set as one pattern, and the pitches P _{1 to} P _n of the one pattern are formed to be the same. Further, as shown in FIG. 14, the area of the square reflecting surface 164 monotonically increases from the inner side to the outer side. Therefore, the proportion of the reflecting surface 164 in the pitch P _{1 to} P _n of the one pattern also occupies. It increases from the inside to the outside (from P ₁ to P _n ) at a constant rate.

On the other hand, the index scale 142 is made of a glass plate having a chromium vapor deposition surface as shown in FIG. 15, and an exit slit 160a parallel to the Y-axis is provided at a position corresponding to the light emitting element 146 on the chromium vapor deposition surface. , 160b and output slits 160c, 160d parallel to the X-axis. Further, the light receiving element 1 on the chromium vapor deposition surface
An entrance slit 158 is provided outside each of the exit slits 160, which are positions corresponding to 48a, ..., 148d.
a, 158b, 158c, 158d are formed.
Therefore, the light L emitted from the light emitting element 146 is emitted, for example, through the emission slit 160a which serves as a secondary light source,
Of the striped grating 152 of the main scale 144, the light is partially reflected by the stripes of the transmissive surface 154a and the reflective surface 164a that are parallel to the Y-axis direction, and is received through the entrance slit 158a.
The light is received by a. That is, of the light radiated on the striped grating 152 of the main scale 144, the light radiated on the transparent surface 154 is not reflected, but only the light radiated on the reflective surface 164 is reflected to the direction of the entrance slit 158a. proceed.

As described above, in the striped grating 152, the ratio of the reflection surface 164 in the pitch P _{1 to} P _n of one pattern of the transparent surface 154 and the reflection surface 164 is constant from the inside to the outside. Since the light is increasing, the light L
The more the position irradiated by is toward the outside of the striped grating 152, the more light is reflected and the amount of light received by the light receiving element 148 also increases. That is, the position of the main scale 144 in the X direction is reflected in the amount of light received by the light receiving element 148a, and thus the displacement of the main scale 144 in the X direction can be grasped by detecting the change in the amount of received light. In addition,
The outputs of the light receiving elements 148a and 148b are voltage outputs differentially amplified by the circuit shown in FIG.

That is, each of the light receiving elements 148a and 148b is composed of a phototransistor, and the current output I _a of the phototransistor 148a is changed by a current / voltage converter 174 composed of an operation amplifier 170 and a semi-fixed resistor 172 connected in parallel. Is output as. Also, the current output I _{b of the} phototransistor 148b
Is output as a voltage change by the current / voltage converter 176 having the same configuration. Each phototransistor 14
8a, the current output I _a of 148b, I _b is because it is anti-phase, as shown in FIG. 17, the differential amplifier 182 consisting of parallel-connected resistors 178 and operation amplifier 180 by a differential amplifier, The voltage output V _out as shown in FIG. 18 can be obtained. Similarly, Y
Even with respect to axial displacement, the transparent surface 154b and the reflective surface 164b parallel to the X-axis direction of the striped grating 152, the exit slits 160c and 160d, and the entrance slits 158c and 158.
d, the light receiving elements 148c and 148d act, and the main scale 1 in the Y-axis direction with excellent linearity
The displacement of 44 can be detected.

Here, the detection sensitivity of the displacement amount of the main scale 144 in the X-axis and Y-axis directions and the detectable displacement range are the transparent surface 154 and the reflective surface 164 of the striped grating 152.
1 pattern pitch width and the amount of increase in the area from the inside to the outside of the square-shaped reflecting surface 164. Tables 1 and 2 show examples in which the pitch width of the one pattern is changed.

[Table 1] ──────────────────────────────────── P ₁ P ₂ P ₃ ...・ ・ ・ ・ ・ ・ P _n-2 P _n-1 P _n ────────────────────────────────── ──Reflecting surface line width (μm) 2 4 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 46 48 50 ────────────────────────── ─────────── Transparent surface line width (μm) 48 46 44 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 42 20 ───────────────── ──────────────────── Reflection surface ratio (%) 4 8 12 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 92 96 100 ──────── ─────────────────────────────

[Table 2] ──────────────────────────────────── P ₁ P ₂ P ₃ ...・ ・ ・ ・ ・ ・ P _n-2 P _n-1 P _n ────────────────────────────────── ──Reflecting surface line width (μm) 2 4 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 96 98 100 ────────────────────────── ─────────── Transparent surface line width (μm) 98 96 94 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 4 20 ───────────────── ──────────────────── Ratio of reflective surface (%) 2 4 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 92 96 100 ──────── ───────────────────────────── In the striped grating 152 in Table 1, the pitch width of the one pattern is 50 μm, and Surface 1 The width of the chromium line forming 64 is increased from the inner side to the outer side by 2 μm per pitch.

Therefore, the number of pitches from pitch P _{1 to} P _n is 25, and the total length from pitch P _{1 to} P _n is 1.
It becomes 250 μm (1.25 mm). Further, in the striped grating 152 in Table 2, the pitch width of the one pattern is 1
The width of the chromium line forming the reflecting surface 164 is increased from the inner side to the outer side by 2 μm per pitch.
Therefore, the number of pitches from pitch P _{1 to} P _n is 50,
The total length from pitch P _{1 to} P _n is 5000 μm
(5 mm). In the example of Table 1, the pitch width is shortened to 1/2 as compared with the example of Table 2, and the increase amount of the chromium line width per pitch is the same as that of the example of Table 2, so 1 pitch from the inside to the outside The increase in the ratio of the reflective surface 164 to the inside is shown in Table 2.
The example in Table 1 is larger than that in Example 1. Therefore, at the same displacement amount, as the pitch width of one pattern is shortened as in the example of Table 1, the reflectance changes abruptly, so that the detection sensitivity is improved. In Tables 1 and 2, 1
Although the pitch width of the pattern is changed, even if the increase amount of the width of the chrome line forming the reflecting surface 164 per pitch is increased, the change of the reflectance is also increased and the detection sensitivity is improved. That is, as the total length from the pitch width of one pattern and the pitch P _{1 to} P _n determined by the increase amount (= the number of pitches) of the reflecting surface 164 per pitch (= the number of pitches) is shorter, the reflectance is more changed. The detection sensitivity will be improved. Therefore,
In the examples of Table 1 and Table 2, the ratio of the total lengths of the pitches P _{1 to} P _n is 1.25 mm: 5 mm = 1: 4, and the pitch is 100 μm. The example of Table 1 in which the width is 50 μm can obtain the detection sensitivity about 4 times.

On the other hand, if the total length from the pitches P _{1 to} P _n is increased, the detection sensitivity will decrease, but of course the displacement detectable position range (-P _X to + shown in FIG. 18).
P _X ) becomes wider. That is, the position range in which the displacement of the main scale 144 can be detected is the range corresponding to the striped grating 152 formed by the transparent surface 154 and the reflective surface 164, and therefore the total length from the pitches P _{1 to} P _n. Is 1.25 mm, the total length of the pitches P _{1 to} P _n is 5 mm, compared to the striped grating 152 of Table 1.
With the striped grating 152, the displacement of the main scale 144 can be detected in the position range of 4 times. As described above, the pitch width of the striped grating 152 and the reflecting surface 164.
A wide dynamic range can be obtained by adjusting the increase amount per pitch of the main scale 144 and designing the total length from the pitches P _{1 to} P _n to an appropriate value. Displacement can be detected with high sensitivity and accuracy in the position range corresponding to the size.

The inclination angle / vibration sensor of the present invention is not limited to the above-mentioned embodiment, but various modifications can be made. For example, the length of the linear member, the shape of the weight, or the like. The shape and the like of the housing can be appropriately set according to the application. Further, in the above-described embodiment, both the inclination angle and the vibration information can be measured by one sensor, but it is possible to measure only one of them. Further, the inclination angle calculation means or the vibration calculation means may be configured to calculate the successive displacement amount based on the respective equations described in the above embodiments, or may be created in advance by using these respective equations. The displacement amount may be output based on the existing table.

[0040]

As described above, according to the tilt angle / vibration sensor according to the present invention, the displacement of the pendulum is directly detected by the displacement detecting means in which the movable scale and the fixed scale are combined, which is the same as the prior art. Since it is not configured to indirectly detect the above displacement by utilizing a change in capacitance or a change in magnetic field, there are few error factors,
Accurate tilt angle and vibration measurements can be performed with a simple configuration, and the sensor can be easily manufactured. Also,
According to the tilt angle measuring method of the present invention, the sensor is rotated to generate a displacement corresponding to the absolute tilt angle in the pendulum, and the tilt angle is measured from the displacement, so that the sensor can be used even if the tilt angle does not change. It is possible to measure the absolute inclination angle at the installation position of with high accuracy at all times.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of a tilt angle / vibration sensor according to an embodiment of the present invention.

2 is an explanatory view of a principle of measuring an inclination angle of the sensor shown in FIG.

FIG. 3 is an explanatory diagram of a measurement principle of a tilt angle measuring method according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a measuring principle of a tilt angle measuring method according to another embodiment of the present invention.

5 is an explanatory diagram of a vibration measurement principle of the sensor shown in FIG.

FIG. 6 is an explanatory diagram of a schematic configuration of a photoelectric encoder used in an embodiment of the present invention.

FIG. 7 is an explanatory diagram of an arrangement of a light emitting element and a light receiving element of the photoelectric encoder used in the embodiment.

FIG. 8 is an explanatory diagram of a movable scale of the photoelectric encoder used in the embodiment.

FIG. 9 is an explanatory diagram of a fixed scale of the photoelectric encoder used in the embodiment.

FIG. 10 is an explanatory diagram of a movement detection principle of the photoelectric encoder used in the above-described embodiment.

FIG. 11 is an explanatory diagram of a schematic configuration of a photoelectric encoder used in another embodiment of the present invention.

12 is an explanatory diagram of the arrangement of light emitting elements and light receiving elements of the photoelectric encoder shown in FIG.

13 is an explanatory diagram of a striped grating formed on a movable scale of the photoelectric encoder shown in FIG.

14 is an explanatory diagram of an area change according to a position of a reflection surface of the striped grating shown in FIG.

15 is an explanatory diagram of a fixed scale of the photoelectric encoder shown in FIG.

16 is a configuration explanatory view of a differential amplifier circuit of a signal from a light receiving element of the photoelectric encoder shown in FIG.

FIG. 17:

18 is an explanatory diagram of a signal processing state by the circuit shown in FIG.

[Explanation of symbols] 10 Inclination / vibration sensor 12 Base 16 Upper lid 17 Housing 18 Wire spring 20 Weight 22 Pendulum 24 Displacement detecting means 28 Movable scale 30 Fixed scale

Front page continuation (72) Inventor Souji Ichikawa 1-20-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Mitutoyo Co., Ltd. No. 1 Mitutoyo Co., Ltd. (72) Inventor Shingo Kuroki 1-20-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Mitutoyo Co., Ltd.

Claims (5)

[Claims] 1. A housing for covering a main part of a sensor, and a pendulum hanging from an upper wall portion of the housing, having a weight attached to a lower portion of a linear body having elasticity in a direction perpendicular to a length direction. A movable scale installed on the lower surface of the weight, and a fixed scale fixed to the bottom wall portion of the housing, the fixed scale being arranged to face the movable scale, and the lengthwise direction of the linear body of the weight. Displacement detecting means for detecting a two-dimensional displacement in a direction perpendicular to the inclination angle, and an inclination angle for calculating an inclination angle at the position where the bottom wall portion of the housing is arranged based on the displacement amount detected by the displacement detecting means. An inclination angle sensor, comprising: an arithmetic means. 2. A housing for covering a main part of the sensor, and a pendulum hanging from a top wall portion of the housing, having a weight attached to a lower portion of a linear body having elasticity in a direction perpendicular to a length direction. A movable scale installed on the lower surface of the weight, and a fixed scale fixed to the bottom wall portion of the housing, the fixed scale being arranged to face the movable scale, and the lengthwise direction of the linear body of the weight. Displacement detecting means for detecting a two-dimensional displacement in a direction perpendicular to the direction, and vibration for calculating vibration information at the position of the bottom wall portion of the housing based on the amount of displacement detected by the displacement detecting means. A vibration sensor comprising: an arithmetic unit. 3. The tilt angle measuring method using the tilt angle sensor according to claim 1, wherein a sensor rotation step of rotating the tilt angle sensor with reference to a central axis of the tilt angle sensor, the pre-rotation position and the post-rotation position. A displacement detecting step of detecting a relative displacement amount between the movable scale and the fixed scale at a position, and an absolute inclination angle with respect to a horizontal plane at a position where the bottom wall portion of the housing is disposed is calculated based on the detected displacement amount. A tilt angle calculating step, comprising: a tilt angle calculating step. 4. The tilt angle measuring method according to claim 3, wherein the sensor is rotated by a predetermined angle in the sensor rotating step,
Based on the rotation angle and the displacement amount detected in the displacement detecting step, the absolute inclination angle in the inclination angle calculating step is expressed as follows: sin θ≈ [R / (1-cosα)] · (3EI / Wl ³ ) Where θ: absolute inclination angle at the position where the bottom wall of the housing is installed R: relative displacement between the movable scale and fixed scale α: sensor rotation angle (0 ° <α <360 °) W: weight center of gravity Concentrated load in E: Elongational modulus of elasticity of linear body I: Moment of inertia of linear body l: Inclination characterized by the distance from the lowest position of the linear body supporting part of the pendulum to the center of gravity of the weight Angle measurement method. 5. The tilt angle measuring method according to claim 3, wherein the sensor is rotated at least twice at an arbitrary angle in the sensor rotation step, and the movable scale is provided at a pre-rotation position and respective post-rotation positions. The radius of the circumscribed circle of the polygon connecting the respective displacement points relative to the fixed scale is obtained, and based on the radius value, the absolute inclination angle is calculated in the inclination angle calculation step as follows: sin θ≈r · (3EI / Wl ³ ) where θ: absolute inclination angle at the position of the bottom wall of the housing r: radius of the circumscribed circle of the polygon that connects the displacement points W: concentrated load at the center of gravity of the weight E: longitudinal of the linear body Elastic coefficient I: Moment of inertia of linear body l: Inclination angle measuring method characterized by being calculated by the distance from the lowest position of the linear body supporting portion of the pendulum to the center of gravity of the weight.